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10. Chronic Respiratory Alkalosis with Acute Metabolic Alkalosis.

This woman lives at an altitude of two miles in Cusco, Peru. In response to hypoxemia she normally hyperventilates with a PCO2 of 28 mmHg. In partial compensation for this chronic respiratory alkalosis she normally maintains a compensatory metabolic acidosis with SBE = -4 mMol/L.

When she develops upper gastro-intestinal obstruction she vomits and, in losing gastric acid, develops a metabolic alkalosis which alters the SBE from her normal value of -4 mMol/L to zero.

If these results were reviewed with no knowledge of the patient's history, they would be mistaken for someone with an acute disturbance, e.g., acute voluntary hyperventilation, or a healthy individual being hyperventilated during minor surgery.

Classical Zones

The diagram shows the position of the principal zones. These zones are based on the review of the literature described by Schlichtig, Grogono, and Severinghaus. The arrows indicate typical acidosis and alkalosis. The labels in the black circles correspond to the legend in the table below.